When a tyre is fitted to a rim, balancing is a common but essential operation. Correcting the poor distribution of mass inside a tyre helps prevent vibrations that intensify with speed and have a negative impact on mechanical components, on-board electronics, tyre wear and driving comfort.
A fine line
Despite all the efforts made by tyre manufacturers, the rim, like the tyre, is not perfect. There are dispersions in the circular distribution of mass that create an imbalance within the wheel when driving. Often, it is insignificant (counted in grams) but with the wheel rotation speed, it causes vibrations that have a knock-on effect on the axles, transmission and steering, right to the steering wheel. For example, an imbalance of 500g may generate a disturbance force of more than 110 kg at 55 mph. A correctly balanced tyre therefore improves driving comfort and protects mechanical components as well ason-board electronics. Tyre wear is more even, which increases its mileage potential and facilitates regrooving and retreading. However, sometimes imbalance is subtle and is not felt at the steering wheel.
Tyre balance should be checked regularly on the whole
rig, since with wear, the mass distribution may vary. Certain specialised brands offer to perform this operation on the professional’s site by sending a technician with a portable wheel balancer. With this practice, you avoid the need to take the truck toa service centre and the truck’s downtime is reduced.
An alternative yet to be validated
Today, the most common balancing technique is to position weights using a machine. This machine is used to correct static imbalance but also dynamic imbalance. There is another solution, however, although there are no tests to prove its efficiency and reliability. This solution consists in placing a bag of microbeads inside the tyre when it is fitted, which tears as the vehicle moves. The microbeads reposition themselves inside the tyre to neutralise the imbalance. Yet, this procedure, depending on the material, its treatment, its surface roughness or the sphericity of microbeads, may damage the inside of the tyre and therefore compromise its airtightness and resistance to oxidation. Furthermore, microbeads tend to make it difficult to position the core inside the valve, which may cause air leakage. It is therefore necessary to use a compatible valve core, often supplied with the bag of microbeads. It is advisable not to use microbeads directly, without their bag, since they may open the bead and reduce the airtightness of the tyre.
By Renaud Lacroix